1. Field of the Invention:
The present invention relates to a vertical axis clothes washer and more particularly to a vertical axis clothes washer having a rotating bottom plate for agitating clothing in the washer.
2. Description of the Related Art:
Attempts have been made to provide an improved automatic clothes washer which uses less energy and water, while providing comparable or superior wash results of present commercially available automatic washers. For example, such an improved washer may advantageously employ the system and processes shown and described in U.S. Pat. Nos. 4,784,666, 4,987,627, and 5,460,018, assigned to the assignee of the present invention, and incorporated herein by reference.
The basis of these systems stems from the optimization of the equation where wash performance is defined by a balance between the chemical (the detergent efficiency and water quality), thermal (energy to heat water), and mechanical (application of fluid flow through--fluid flow over--fluid impact--fabric flexing) energy inputs to the system. Experience has shown that any reduction in one or more energy forms requires an increase in one or more of the other energy inputs to produce comparable levels of wash performance.
Typically, a conventional vertical axis washer functions by loading fabric items to be washed into a vertically oriented wash basket disposed within a wash tub and further having a vertically orientated agitator centrally supported within the wash basket. Detergent and water are supplied into the tub and basket for forming a wash liquid such that the fabric items are completely submerged in wash liquid, and wherein the oscillation of the agitator causes the clothes to move in the wash liquid within the wash basket. In this configuration, the detergent provides a chemical energy input, the introduction of hot/warm water for mixing with the detergent provides a thermal energy input, and the action of the agitator provides a mechanical energy input, whereby all of these energy inputs act together to remove soil from the fabric items.
Traditionally, this system of washing requires a large amount of water, as much as 46 gallons for one clothes load, to suitably wash clothes. This is due to the fact that for the oscillating agitator to properly apply mechanical energy to the clothes without damaging them, all of the fabric items must be substantially submerged in wash liquid. The agitator imparts mechanical energy to the clothing by direct contact and agitation of the water. This complete submersion of the fabric items occurs during the wash cycle and each of the subsequent rinse cycles.
In addition to an oscillating agitator, it is also known for automatic washers using a submersion method to include a rotatable plate having one or more paddles disposed at the bottom of the wash basket to agitate the circulation of water within the wash basket to increase the movement of the clothing and their frictional interaction to add mechanical energy to the system. These systems are commonly referred to as impeller automatic washers. In impeller washers, very little, if any, of the mechanical energy is imparted from the impeller directly to the clothing. Almost all of the mechanical energy is imparted to the clothing through the agitation of the water. Examples of such impeller-type automatic washers are illustrated in U.S. Pat. Nos. 5,239,847, issued Aug. 31, 1993, 4,862,710, issued Sep. 5, 1989, and 2,575,691, issued Nov. 20, 1951.
U.S. Pat. No. 3,087,776, issued Apr. 30, 1963, discloses an automatic washer having a rotatable tub with an integral ramp whereby upon the rotation of the tub, clothing is dropped over the end of the ramp to agitate the clothing as it falls downwardly. Further, a transducer is positioned in the end of the ramp to impart vibratory movement via sound waves to the wash liquid to further agitate the clothing falling beyond the end of the ramp.
To substantially reduce the amount of wash liquid used in a vertical axis washer, alternate means for inputting mechanical energy to the wash load have been contemplated that do not require complete submersion of all the fabric items. Pending U.S. patent application Ser. No. 07/815,781, Kovich et.al., assigned to the assignee of the present invention and incorporated herein by reference, discloses a vertical axis washer utilizing a system for imparting mechanical energy into the fabric items wherein a substantial reduction in water consumption may be achieved. In this system the washer is provided with a basket having a ramp and baffle extending inwardly from the basket.
Other systems for imparting mechanical energy into fabric items clothes load in a vertical axis washer are also known. In U.S. Pat. No. 2,802,356 to Kirby, a vertical axis washer is provided wherein a wash basket is disposed within a tub. No agitator is provided for agitating the clothes, rather, the wash basket is mounted for providing a wobbly motion within the tub such that during the wash cycle, the basket is filled with wash liquid and is given a wobbling motion which agitates and distributes the clothes and thoroughly washes them.
In U.S. Pat. No. 2,145,453 to Miller a vertical axis washer is provided having a bottom plate mounted for gyratory motion within a wash tub. No wash basket is provided. During wash, the bottom plate is driven in a gyratory oscillating movement such that the clothes are agitated. Miller teaches the complete submersion of the fabric item within wash liquid during the wash cycle.
Significantly greater savings in water usage and energy usage than is achieved by heretofore disclosed vertical axis wash systems are highly desirable and would be an improvement in the art. Furthermore, it would be a significant improvement in the art to provide a system for imparting mechanical energy to fabric items in a vertical axis washer without requiring complete submersion of the clothes with wash liquid.